/Engine/Source/Runtime/Core/Public/Misc/ExpressionParserTypes.h
Examples that binds a '!' token to a function that attempts to do a boolean 'not': JumpTable.MapPreUnary({ return !A; }); JumpTable.MapPreUnary({ if (Ctxt->IsBooleanNotOpEnabled()) { return !A; } else { return A; } }); JumpTable.MapPreUnary(-> FExpressionResult { if (Ctxt->IsBooleanNotOpEnabled())
{
    return MakeValue(!A);
}
return MakeError(FExpressionError(LOCTEXT("NotNotEnabled", "Boolean not is not enabled.")));
 });
template<typename OperatorType, typename FuncType> void MapPreUnary ( FuncType InFunc )